1. Field of the Invention
The present invention relates to a method for manufacturing a substrate of liquid crystal display (LCD) devices, and more particularly to a method for manufacturing a substrate of thin film transistor (TFT) LCD devices.
2. Description of Related Art
Currently, manufacturers of integrated circuits have progressed to the stage of ultralarge scale integration (ULSI). Because of cost of manufactured integrated circuits and driving rate of elements, manufacturers of back-end metal lines have a tendency to produce multilayers and fine metal lines. A first problem experienced by the manufacturers of metal conductive line fining is a capacity effect, which reduces signal-transmitting rate, produced from insulation layers between metal layers.
The transmitting rate of circuit signals is determined by product of resistance (R) and capacity (C), and the smaller RC product means the faster transmitting rate. In traditional methods for solving signal delay of internal metal conductive lines, metal with lower resistance is commonly used to make metal conductive lines, or insulating material with lower dielectric constant is used to make insulation layers between metal layers. These methods do cause the signal-transmitting rate of conductive lines to be improved.
Comparing to conventional CRT monitors, LCD devices have advantages of low consumption of electricity, compact size, and no radiation. While contemporary requirements of TFT LCD devices have a tendency to large panel size and high image resolution, RC delay in signal-transmitting rate of metal conductive lines is in fact more critical. In order to improve transmitting rate of signals driven by TFTs, metals with low resistance for example, copper, silver, gold etc. are applied to make metal lines or gate electrodes of substrates of flat panel display devices. Therefore, the problem of driving signal delay can be solved.